Commercial printers often prefer to receive a PDF file for printing.
Here are the steps for saving a publication as a PDF:
Click File > Export > Create PDF/XPS Document > Create PDF/XPS.
Under File name, type a name for the publication.
Click Options and choose the publish option best for online or print viewing of your publication:
Minimum Size Use this option for online viewing as a single page
Standard Use this option for online distribution such as email when a recipient might print the publication on a desktop printer
High Quality Printing Use this option for either desktop or copy shop printing
Commercial Press This option creates the largest and highest quality files for commercial printing
Click OK, and click Publish.